This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 USC §552a and has been cleared for distribution.

1

GSI White Paper

Issues Raised in February 21, 2013 Work Group Meeting

Prepared by David Allen, DCAS

April 2013

Background

During the meeting of the TBD-6000 Work Group on February 21, 2013, the Work Group 

requested that NIOSH provide details pertaining to three issues. The issues were:

1. Describe the external dose estimate NIOSH intends to use for non-radiographers prior to 

1963.

2. Describe how individual cases will be assigned to different job categories. 

3. Describe the internal dose estimate that will be used.

This paper provides the requested information.

Non-Radiographer Dose Estimate pre-1963 (Radium Era)

Prior to the Work Group meeting, NIOSH provided a white paper summarizing the dose 

estimates made by NIOSH and SC&A for various tasks at GSI (NIOSH 2013). When discussing 

the use of radium radiography (prior to 1963) both agreed the majority of radiography with the 

small isotopic sources occurred inside the radiography room, but NIOSH had not produced a 

dose estimate for that scenario. In the summary, NIOSH indicated their intent to use the SC&A 

estimate. Some issues with that estimate were discussed in the Work Group meeting and NIOSH 

was asked to develop and describe the model they intend to use.

In developing a model, the survey of the radiography room performed in August of 1962 was 

deemed the best available data since it represented actual measurements. This survey, however,

was performed with Co-60 sources in place and after the shielding of the room had been

modified. Therefore, the survey measurements must be adjusted to make them applicable to the 

radium radiography.

The initial license application to the Atomic Energy Commission from GSI (dated 4/18/1962) 

indicated the walls of the radiography room were 16” thick solid concrete (AEC 1962). On 
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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

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2

September 7, 1962, GSI sent the AEC a copy of a survey of the radiography room (Kleber 1962). 

The survey report indicated measurements were made on June 24 and August 1 of 1962. This 

survey report also indicated the walls were 24 inches thick and included a sketch of the room 

with the annotation “Shows additional shielding added during June-July 1962”. Therefore, it is 

assumed that an additional 8 inches of concrete were added to the room in June and July of 1962 

prior to the survey performed on August 1, 1962.

As described in a previous white paper (NIOSH 2011), the two 500 mg radium sources were 

used until they were replaced with two Co-60 sources of strength 0.28 Ci and 0.26 Ci in 1962. 

The exposure rate from the two radium sources is actually slightly higher than from the Co-60 

sources. This difference as well as the difference in shielding effectiveness and shielding 

thickness must be accounted for to determine the exposure rates from the radium radiography.

From the previous white paper, the two radium sources would each produce an exposure rate of 

4.44 R/hr at one foot while the Co-60 sources would produce an exposure rate of 3.98 R/hr and 

3.69 R/hr at one foot. Two sources together would then produce an exposure rate of 8.88 R/hr 

for the radium sources and 7.67 R/hr for the Co-60 sources. The half-value layer (HVL) of 

concrete for Radium and Co-60 is 6.9 cm and 6.2 cm, respectively (Williams and Wilkins 1998). 

Therefore, 24 inches of concrete would reduce the exposure rate from the Co-60 sources by a 

factor of 912. Also, 16 inches of concrete would reduce the Radium exposure rate by a factor of 

59. 

The survey performed August 1, 1962 indicated the maximum reading one meter above the floor 

outside the room was 1.2 mR/hr while the average was 0.15 mR/hr. The report further indicated 

the 0.15 mR/hr average included a background level of 0.05 mR/hr and that most readings did 

not exceed the background level. 

Based on shielding and source strength, the maximum observed reading of 1.2 mR/hr through 24 

inches of concrete would require that both Co-60 sources be exposed at a distance of 32 inches

from the survey meter, 24 of which is the concrete wall. Thus, both sources would have been

only 8 inches from the inside wall, while the survey meter was in contact with the outside of the 

wall. This would not represent a realistic scenario for an individual routinely working near the 

radiography room. Even if an individual always worked next to the room, it is not reasonable to 
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 USC §552a and has been cleared for distribution.

3

assume he was always pressed against the wall and always immediately adjacent to where the 

sources were being used. The initial license application (AEC 1962) indicates the sources are 

normally place inside the castings and normally four to six feet from the wall of the room. Also, 

an interview with a former radiographer (SC&A 2011) indicates two radium sources could be 

used to make separate exposures with lead blocks used to shield each film from the source used 

for the adjacent exposure. Lastly, it would be very difficult to place and remove two sources 

with accurate enough timing to achieve the appropriate film exposure. Based on this, it is 

unlikely two sources were used simultaneously without some shielding between them.

For the reasons discussed above, this estimate will use the average reading of 0.15 mR/hr from 

the 1962 survey. This will account for the fact that the individual could be working anywhere 

along the length or the room or the sources could be used anywhere along the length of the 

shooting area inside the room. It does not reduce the estimate to account for the fact that the 

sources are often placed inside casting or that they are not normally placed that close to the 

inside of the wall. It also does not reduce the dose estimate to account for the likelihood that a 

particular individual did not likely stay pressed against the wall of the room 100% of his work 

year. However, the estimate will consider that the measurements were taken with 2 sources 

exposed. Even though it was reported that both sources would sometimes be exposed (SC&A 

2011), it was also reported that radiographers would shield one source from the other so that 

each film would receive the proper exposure. This implies the combined effect of two sources 

near the same location would not occur.

Increasing the average measured exposure of 0.15 mR/hr to account for the stronger radium 

source strength and the 8 inch difference in shielding thickness, results in an exposure rate of 

2.67 mR/hr. However, the report indicated the 0.05 mR/hr background level was included in that 

measurement which means only 0.1 mR/hr was due to the Co-60 sources. Using this value, the 

estimated average exposure rate outside the wall would be 1.78 mR/hr. If it is further assumed 

that both radium sources were not routinely used side by side and the second source (when used) 

was adequately shielded to avoid additional exposure to film, the exposure rate outside the wall 

can be reduced by two, resulting in an estimated exposure rate of 0.89 mR/hr. This exposure rate 

for 975 hr/yr (30% of 3250 hr) results in an annual exposure of 868 mR.
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 USC §552a and has been cleared for distribution.

4

Assignment of Individual Cases to Radiographer vs. non-Radiographer Dose Estimate pre1963 (Radium Era)

During the working group meeting February 21, 2013, a dose estimate for radiographers was 

agreed upon. The estimate results in a triangular distribution with the maximum dose set to the 

annual dose limit of 12 rem (15 rem in 1953 and 1954). The mode value was to be 9.69 rem and 

the minimum 6.279 rem. While the maximum value was based on the regulatory limit, the other 

two values were based on a calculation utilizing the same description of a technique (the fishing 

pole technique) but different parameters reported by a former radiographer. A large part of the 

dose in both these estimates resulted from the placing and removing of the radium sources using 

the fishing pole technique. This estimate is applicable to anyone who may have routinely placed 

or removed sources using this technique (radiographers) but is not applicable to those who did 

not. 

For those that did not place sources, the non-radiographer dose estimate is more applicable. That 

estimate assumes someone is working next to the radiography room 100% of their time. In order 

to assign claims to one category or the other, a two step process is proposed. The process would 

assign a claim the radiographer dose if:

Step 1 – the job title given to DOL matches one of the titles listed below:

The job titles considered possible radiographers includes any variation of the following list.

- Quality Control

- Film reader

- Radiographer

- Inspector

- Betatron

- Magnaflux operator

- Metallurgy department 

- X-ray
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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

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5

Step 2 – indications from the telephone interview that the individual may have performed 

radiography. In the case of no telephone interview, initial claim forms and other information are 

reviewed.

In order to test the process, 284 GSI cases existing in the claim database were searched for these 

job titles (and variations) resulting in 21 claims matching the list. While the telephone interview 

would also be reviewed when a dose estimate is performed, not all were reviewed for this 

exercise. Instead, they were reviewed if:

- They were one of the 21 selected from the first step;

- They had a job title listed as “unknown” or a variation of unknown; or

- The Energy Employees last name matched a name on the Landauer film badge reports.

Of the 21 claims assigned as radiographers by job title, 11 were confirmed to be radiographers 

by telephone interview or dose records. Ten could not be confirmed to be radiographers. Of the 

10 unconfirmed, 1 was a Quality Control Inspector (two other QC inspectors were confirmed), 8 

were inspectors (other than QC inspectors) and 1 was a magnaflux operator. 

The magnaflux operator only worked a few months at GSI and likely was not a radiographer 

since radiographer was generally considered a more senior job. Interviews with the inspectors 

(other than QC inspectors) indicated they most likely were not radiographers but inspected 

dimensions and other aspects of the castings. The one QC inspector that could not be confirmed 

was likely not a radiographer based on his telephone interview. However, there is no discernible 

difference between the description of his job duties and that of some of the non-QC inspectors 

reviewed. This combined with the confirmation that two QC inspectors can be confirmed to be 

radiographers illustrates the need to include any type of “inspector” in the radiography category.

Besides the 21 claims above which were categorized based on job title, an additional 23 

telephone interviews were reviewed for claims with job titles of “unknown”. Most of the 23 

“unknown” claims had job titles or a description of their work provided in the telephone 

interview. Others had work locations identified that indicated the individual was not a 

radiographer. Three had neither. One of those worked entirely during the residual 

contamination period and that dose estimate would not be affected by this determination. The 
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

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6

second worked at GSI for only one day so it is unlikely he would have been trained at 

radiography. The third had no information about job title or duties or location. This one was 

considered a radiographer due to lack of information. However, the employee worked through 

the period when film badges were issued and his name did not appear in film badge records so it 

is likely he was not actually a radiographer. 

An additional two of the 23 “unknown” claims were considered radiographers because of their 

telephone interviews. One of them was confirmed to be a radiographer by dose records and 

information in the phone interview. The remaining one could not be confirmed by any other 

means. The claim was added because of a description of magnaflux operator. However, the 

employee worked through the period when film badges were issued and his name did not appear 

in film badge records so it is likely he was not actually a radiographer. 

Landauer dose records included only the last name of employees issued badges. Thirty one 

names from the claims database matched a last name from the Landauer records. Of those, 11 

had already been added in previous steps. Two were added to the list of radiographers based on 

their telephone interviews. The remaining 18 contained information in job titles, description of 

duties or other information that indicated they did not perform radiography. Most of the 18 were 

the result of a common last name. For example, one name appears in the dose records that 

matched 6 different claims. The individual actually associated with that dose record could be 

confirmed thereby indicating the other 5 were not actually listed on the dose records. Even in the 

case of an uncommon name, the actual radiographer was confirmed but an additional case with 

the same uncommon name appeared in the claims database. This resulted in the realization that 

using these dose records to confirm a person was a radiographer is not foolproof and must be 

considered with other evidence. 

In conclusion, the 2 step process resulted in 26 claims being assigned to the radiographer 

category with 12 of them being confirmed by either telephone interview or dose records or both. 

It is likely additional claims would be added to the category if every telephone interview had 

been reviewed for this exercise. While it is likely some who were not radiographers were 

included in the list, every individual known to be a radiographer and to have a claim was 

identified in the proposed process.
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 USC §552a and has been cleared for distribution.

7

Internal Dose Estimate

The internal dose estimate will start with the airborne concentration agreed to in a previous Work 

Group meeting and reported to the full Board in December 2013. The concentration to be used is 

the 95th percentile of a surrogate data set resulting in an airborne concentration of 68.7 dpm/m3

. 

The airborne is assumed to be present when handling uranium metal. The uranium shot scenario 

provided by workers and used in the external dose estimates is a 60 minute shot with 15 minutes 

between shots, with no one present during the 60 minute shot. The exposure to the airborne in 

that area is then 20% of the total time working with uranium. The time worked with uranium 

was estimated from purchase orders. This only represents the inhalation of uranium while 

handling uranium metal. There is also the possibility of uranium corrosion products being 

deposited on the floor resulting in resuspended contamination being inhaled at other times.

An analysis of the settling of airborne contamination was conducted as part of the Battlle-TBD6000 review. The analysis concluded that the maximum contamination can be determined by 

assuming the airborne contamination settles at a rate of 0.00075 m/s for 30 days. Starting with 

the 95th percentile airborne concentration (68.7 dpm/m3

) this would result in a surface 

contamination of 1.34 x 105 dpm/m2.

This contamination level can be used to estimate the airborne activity due to the resuspension of 

the contamination. ORAUT-OTIB-0070 provides a value of 1x10-6 m-1 during the residual 

period. However, for the period of time between the handling of uranium metal, the 

contamination is not “aged” nor would the conditions in the facility be considered “quiescent”.

Because of this the use of the default value in OTIB-0070 may not be applicable. ORAUTOTIB-0070, however, does supports a factor 10 higher under the conditions described above. 

Therefore, the TBD will use a resuspension factor of 1x10-5 m-1 during the operational period of 

the site and 1x10-6 m-1 during the residual period.

Applying these resuspension factors to the surface contamination value results in airborne 

contamination of 1.34 dpm/m3 to be applied for 3250 hours per year and to all people during the 

operational period. During the residual period, the value of 0.134 dpm/m3 will be applied.
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 USC §552a and has been cleared for distribution.

8

Ingested activity will be determined using OCAS-TIB-009. According to TIB-9, the daily 

ingestion can be estimated as 20% of the airborne concentration in one cubic meter of air. The 

assumption of TIB-9 assumes an 8 hour work day. This value can be adjusted to a 3250 hour 

work year by dividing the value by 8 hours then multiplying it by 3250 hours. This results in an

ingestion rate of 5582 dpm per year or 15.3 dpm per calendar day. 3250 hours per year is used 

for both resuspended airborne and ingestion since surface contamination is not necessarily 

limited to the shooting area. By assuming contamination levels similar to where the uranium 

was routinely handled, this represents a claimant favorable estimate. 

All individuals will receive the same internal dose estimate. This is due to the fact that the 

highest airborne activity would be located in the betatron buildings where the uranium was 

positioned for an x-ray. Others besides radiographers also frequented the building and would be 

exposed regardless of their task. 

As indicated in Appendix BB revision 0, inhalation and ingestion values will be multiplied by 

1.01 to account for fission products that may have been produced during the x-ray examination. 

A summary of the values discussed in show in the table below.

Start Date End Date Uranium 

work 

(hr/yr)

Inhalation 

from 

Handling 

(dpm/day)

Inhalation 

from 

resuspension 

(dpm/day)

Total 

inhalation 

(dpm/day)

Ingestion 

(dpm/day)

1/1/1953 6/30/1961 337.5 15.40 14.41 29.81 15.45

7/1/1961 6/30/1962 437.5 19.96 14.41 34.37 15.45

7/1/1962 6/30/1963 125 5.70 14.41 20.12 15.45

7/1/1963 6/30/1965 28 1.28 14.41 15.69 15.45

7/1/1965 6/30/1966 13 0.59 14.41 15.01 15.45

After 

6/30/1966

1.44 1.44 15.45

Note: the values after 6/30/1966 are to be reduced using depletion factors in ORAUT-OTIB-0070.
This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH 

or ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 USC §552a and has been cleared for distribution.

9

References

AEC 1962, Initial Byproduct Material License for General Steel Industries with application, 

Atomic Energy Commission, NRC Accession Number ML093431334, April 18, 1962

Kleber 1962, Letter transmitting survey of radiographic exposure facility to the James 

Mason, AEC, NRC Accession Number ML093431294, September 7, 1962

NIOSH 2011, Battelle-TBD-6000 Appendix BB General Steel Industries Dose Estimates for 

Portable Radiography Sources, NIOSH white paper, August 2011

NIOSH 2013, GSI Dose Estimation Comparison, January 2013

SC&A 2011, Update of the Use of Sealed Radioactive Sources at General Steel Industries, 

SC&A draft white paper, October 2011

Williams and Wilkins 1998, Handbook of Health Physics and Radiological Health, Third 

Edition